Electric-arc lamp



(No Model.)

. R. 0. HOOD.

ELECTRIC ARC LAMP.

No. 574,905. Y Patented Jan. 12, 1897.

ATTORNEY.

UNITED STATES PATENT OFFICE.

RALPH O. HOOD, OF DANVERS, MASSACHUSETTS.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 574,905, dated January12, 1897.

Application filed July 6,1896. Serial No. 598,064. \No model.)

To ctZZ 1071,0111, it may concern:

Be it known that I, RALPH O. HOOD, a citizen of the United States,residing at Danvers, in the county of Essex and State of Massachusetts,have invented certain new and useful Improvements in Electric-Arc Lamps,of which the following is a specification.

My invention relates to electric-arc lamps particularly adapted for useon multiple-arc or constantpotential circuits.

The object of this invention is the production of a lamp which shallhave the quality of steadiness in its operation, the ability to quicklyand steadily draw and form the are without the make-and -breal effectwhich causes violent hammering of the parts that is liable to occur whenlamps are operated across a low-potential circuit of approximatelythirty volts, and which shall only necessitate the use in itsconstruction of asniall magnetic force for its operation, thereby doingaway with the humming noise caused by strong alternati n g magneticfields acting upon the metallic cover when the lamp is used onalternating circuits.

The invention consists of a device for holding the carbons which isacted upon by the expansion of a mass due to the heating effect of theelectric current in such a manner as to draw and form the arc, and anelectromagnetic device placed in series with the are for drawing orfeeding the carbons together as they are burned away.

It also consists in a device for preventing the overheating of theaforesaid mass in cases where the current is switched on and off sorapidly as to normally prevent the mass from cooling each time.

' I hereinafter describe one of the many mech anisms in which myinvention may be embodiedrbut it will be understood that I do not limitmyself thereto, as many and various changes maybe made withoutdepartingfrom its spirit and scope.

Reference is to be had to the annexed drawing, and to the letters markedthereon, forming a part of this specification.

The drawing shows diagrammatically the different parts of the lamp.

A mass, preferably in the form of a highresistance wire, is representedby a. b is a magnet acting upon the armature c, which is supported bythe spring d. Attached to the armature is the detent-arin 6, arranged toengage with the escapement-arm j, which is rigidly connected to theescapement g, as hereinafter described. The carbon-rod h is connected bymeans of its rack and the gears t' to the escapement-wheelj, the trainof gears and the escapement being placed in the frame is, pivoted at oneend upon the pi vot-blockl and held at its other end by the spring mfrom the stationary block m. n and at represent the upper and lowercarbons, respectively. The wire a is fastened at one end to the frame 7cand at the other end to the insulated stationary block 0.

The armature c is prevented from getting out of magnetic range of themagnet 11 by means of the stop 1).

(1 represents a detent for engaging with the escapement when the wire ahas expanded to an unusual degree.

The binding-posts or terminals of the lamp are shown at 0' and r, thepath of. the current being from binding-post 1, through magnot 1), wirea, frame 76, carbon-rod h, carbons n n, to binding-post r.

The operation of the lamp is as follows: When the lamp is out ofcircuit, the carbons are together and the wire a is in a natural stateof linear expansion, being shorter than is shown in the drawing, whichrepresents the lamp in operation, and has therefore pulled the framedown from the position shown in the drawing, extending the spring m.Upon the establishment of a current the wire a is warmed, due to thecurrent flowing through it, and by its expansion due to heat allows thespring m to bring the frame into the position shown in the drawing,thereby separating the carbons and forming the are. If the arc becomestoo long and the strength of the current falls below the predeterminedamount that should flow through the lamp, the action of the magnet 12 isweakened to a sufficient extent to allow the spring (1, which would holdthe armature 0 against the stop 19 were no current passing, to move thearmature in such a position as to free the escapement by means of thearm 6, releasing the arm f. The carbons will then by force of gravity ofthe carbon-rod h, operating the gears 't' and the escapement, cometogether near enough to increase the current flow to a sufficient extentto cause the arm e to again engage the escapement mechanism on accountof the in crease of strength of the magnet.

In practice the feeding will be so gradual that the escapement will onlyfeed one or two teeth at one action of the armature 0, but should thefeed be greater than is really necessary to keep the current constantthe increase of current will expand the wire a to a greater extent andthereby preserve a balance.

It will be clearly seen that a very slight magnetic force will performthe above-described operation.

I have found that as the action of the wire a in drawing the arc is muchslower than that of a magnet the are is always drawn successfully fromthe first separation of the carbons, while were a magnet employed theestablishment of a current would cause it to act so rapidly as to breakthe are, owing to the quickness of the sepz'n'ation of the carbons. Thiswould cause a rapid succession of endeavors to form an arc until asufficient amount of carbon vapor h ad been formed to maintain the areunder the low potential which might be used. it

I understand that dash-pots and retarders of different kinds could beused for retarding the action of a magnet, but said retarders would beless constant and reliable as well as more expensive than an expandingcond uctor.

If in the device which I have just described the current is switched offand then immediately turned on again, the carbons will touch each otherbefore the wire a has come to the temperature of the surrounding air,and as said wire has to expand to a given amount to draw the are it willstart from a fairly high temperature and arrive at a temperature abovethe normal when the arc has been formed. If this operation be repeatedsuccessively, it will be seen that the wire will be increasing intemperature each time until a point is reached which will injure it. Toavoid this, I place a stationary catch or detent q for engaging with theescapement when the wire is in a state of expansion above the normal andthereby prevent the feeding of the carbons together. This has the effectof avoiding the successive increments of heat in the wire a due to thecontinual rapid switching on and off of the current, for the reason thatthe wire must go down to its normal temperature before the carbons cancome in contact, and said wire is so arranged as to safely stand theincrease of temperature necessary to draw the are when starting fromsaid normal heating-point.

I am aware that a metallic mass expanding under the action of theelectric current has been used to separate the carbons in anelectric-arc lamp; but I believe that the feeding of the carbonstogether has heretofore been accomplished by other means than that of amagnet acting in series and in conjunction with the mass and possessingthe advantages which I have pointed out.

IIavin g thus explained the nature of my in vention and described a wayof constructing the same, though without attempting to set forth all theforms in which it may be made or all the modes of its use, it isdeclared that what is claimed is- 1. In an electricarc lamp, thecombination of a mass whose expansion under the action of the electriccurrent separates the carbons employed therein and a magnet in serieswith the are for feeding the carbons toward each other when the currentflowing across the are is at a predetermined value.

2. In an. electric-are lamp, the combination of a mass whose expansionunder the action of the electric current flowing througl'i said massdraws and forms the arc and a magnet in series with the are formaintaining the arc and preventing the current from falling below apredetermined value.

3. In an electric-arc lamp, a mass expansible under the action of theelectric current flowing through it for the purpose of moving a devicewhich holds the carbons, under the control of a magnet in series withthe are, in such a manner as to strike the are in combination with saidmagnet for releasing the hold of the carbons when the current flowingthrough said mass and the arc is at or below a predetermined value.

1-. In an electric-arc lamp, a metallic mass expansible under the actionof the electric current and operating a device for sepz'irating thecarbons and thereby forming the are in combination with anelectromagnetic device placed in series with the are for releasing orfeeding the carbons when the current [lowing between said carbons is ator below a fixed value.

5. In an electric-arc lamp, the coi'nbination of a metallic mass whoseexpansion due to the flow of the current separates and keeps the carbonsapart, a clock-escapemmit device for feeding the carbons and a magnet inseries with the are arranged to permit of the operation of saidescapemcl'it device when the current flowing through the metallic massand the arc falls to a predetermined amount.

6. The combination in an electric-arclamp of a wire, in series with theare, whose ex pansion due to the heat caused by the .tiowof the currentpermits of the separation of the carbons and a magnet, in series withthe arc, whose action, when the current falls below the amount desiredto flow through the lamp, is to permit of the feeding of the carbons,sub stantially as and for the purpose described.

7. In an electric-arc lamp, the combination of a mass whose expansionunder the action of the electric current separates the carbons employedtherein, a magnet for feeding the carbons toward each other, with adetent for preventing said feeding when said mass has expanded to adegree above the normal, as and for the purpose described.

RALPIIL 0. H001). \Vitnesses:

' W. Knrrn, STABLER.

